U.S. patent application number 11/562128 was filed with the patent office on 2007-06-07 for apparatus and method for determining the viability of eggs.
Invention is credited to Sidney James Reeves, Ketih Angus Simpson.
Application Number | 20070125305 11/562128 |
Document ID | / |
Family ID | 9913172 |
Filed Date | 2007-06-07 |
United States Patent
Application |
20070125305 |
Kind Code |
A1 |
Reeves; Sidney James ; et
al. |
June 7, 2007 |
APPARATUS AND METHOD FOR DETERMINING THE VIABILITY OF EGGS
Abstract
An apparatus (10) for determining the viability of an egg, which
apparatus (10) comprises shielding means (12, 14), emitting means
(30) and detecting means (32), the arrangement being such that, in
use, the shielding means (12, 14) inhibits exposure of an egg to
background infra-red radiation, said emitting means (30) can emit
electromagnetic radiation at infra-red wavelength(s) to impinge on
the egg, and the detecting means (32) are positioned to detect at
least a part of said electromagnetic radiation that has passed
through the egg, the apparatus further comprising means for
processing an output signal of the detecting means to determine
whether there is a cyclical variation in the intensity of the
infra-red radiation leaving the egg corresponding to action of a
heart, the existence of said cyclical variation indicating that the
egg is viable.
Inventors: |
Reeves; Sidney James;
(Truro, GB) ; Simpson; Ketih Angus; (Torquay,
GB) |
Correspondence
Address: |
ANTHONY R. BARKUME
20 GATEWAY LANE
MANORVILLE
NY
11949
US
|
Family ID: |
9913172 |
Appl. No.: |
11/562128 |
Filed: |
November 21, 2006 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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10475229 |
Oct 17, 2003 |
7154594 |
|
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PCT/GB02/01784 |
Apr 17, 2002 |
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11562128 |
Nov 21, 2006 |
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Current U.S.
Class: |
119/6.8 |
Current CPC
Class: |
A01K 45/007 20130101;
G01N 33/085 20130101; G01N 21/359 20130101; G01N 21/3563
20130101 |
Class at
Publication: |
119/006.8 |
International
Class: |
A01K 45/00 20060101
A01K045/00 |
Foreign Application Data
Date |
Code |
Application Number |
Nov 21, 2006 |
GB |
0109765.8 |
Claims
1-49. (canceled)
50. An apparatus for determining the viability of an egg, which
apparatus comprises, an emitter and a detector, the arrangement
being such that, in use, said emitter can emit electromagnetic
radiation that impinges on the blunt end of the egg, and the
detector is positioned to detect at least a part of said
electromagnetic radiation that has passed through the egg, the
apparatus further comprising electronic processing equipment for
processing an output signal of the detector to determine whether
there is a superimposed cyclical variation in the intensity of the
radiation leaving the egg corresponding to action of a heart, the
existence of said superimposed cyclical variation indicating that
the egg is viable, characterised in that said emitter can emit
electromagnetic radiation at infra-red wavelength(s) but not at
optical wavelengths and said detector can detect infra-red
radiation leaving said egg, whereby said superimposed cyclical
variation is detectable up until the animal hatches from the
egg.
51. An apparatus as claimed in claim 50, wherein said electronic
processing equipment is configured to process said output signal
such that it may be used to provide a visual display trace on which
any superimposed cyclical variation is apparent.
52. An apparatus as claimed in claim 50, wherein said electronic
processing equipment can determine a heart rate and provide a heart
rate output signal suitable for displaying a numerical indication
of the heart rate on a display.
53. An apparatus as claimed in claim 50, wherein the means for
processing extracts only variation in the output signal.
54. An apparatus as claimed in claim 50, wherein said electronic
processing equipment can extract the time interval between
successive points in the superimposed cyclical variation in order
to calculate a heart rate therefrom.
55. An apparatus as claimed in claim 54, wherein said electronic
processing equipment can compare the calculated heart rate against
a predetermined range to ensure that the calculated heart rate lies
within the range to inhibit the effect of random noise.
56. An apparatus as claimed in claim 54, wherein said electronic
processing equipment can extract a plurality of time intervals, and
is able to calculate an average time interval and an average heart
rate therefrom.
57. An apparatus as claimed in claim 56, wherein said electronic
processing equipment can compare the calculated average heart rate
against a predetermined range to ensure that the calculated average
heart rate lies within the range to inhibit the effect of random
noise.
58. An apparatus as claimed in claim 50, wherein said emitter emits
electromagnetic radiation over a limited angle.
59. An apparatus as claimed in claim 58, wherein said limited angle
is adjustable.
60. An apparatus as claimed in claim 50, wherein the emitter emits
electromagnetic radiation in the wavelength range 720 nm to 940
nm.
61. An apparatus as claimed in claim 60 wherein the emitting means
emit electromagnetic radiation predominantly at a wavelength of 875
nm.
62. A method of determining the viability of an egg, which method
comprises the steps of: (1) emitting electromagnetic radiation from
an emitter toward the blunt end of said egg; (2) detecting at least
a part of said electromagnetic radiation that has passed through
the egg with a detector and generating an output signal therefrom;
and (3) processing said output signal to determine whether there is
a superimposed cyclical variation in the intensity of the radiation
leaving the egg corresponding to action of a heart, the existence
of said superimposed cyclical variation indicating that the egg is
viable; characterised in that step (1) is performed by emitting
electromagnetic radiation at infra-red wavelength(s) but not at
optical wavelengths toward said egg and step (2) is performed by
detecting electromagnetic radiation at infra-red wavelengths that
has passed therethrough, whereby said superimposed cyclical
variation is detectable up until the animal hatches from the
egg.
63. A method as claimed in claim 62, further comprising the step of
providing a visual display trace on which any superimposed cyclical
variation is apparent.
64. A method as claimed in claim 62, further comprising the step of
processing said output signal to determine a heart rate and
displaying a numerical value of the heart rate to a user.
65. A method as claimed in claim 62, further comprising the step of
extracting only variation in the output signal.
66. A method as claimed in claim 62, further comprising the step of
extracting the time interval between successive points in the
cyclical variation in order to calculate a heart rate
therefrom.
67. A method as claimed in claim 66, further comprising the step of
comparing the calculated heart rate against a predetermined range
to ensure that the calculated heart rate lies within the range to
inhibit the effect of random noise.
68. A method as claimed in claim 66, further comprising the step of
extracting a plurality of time intervals, and calculating an
average time interval and heart rate therefrom.
69. A method as claimed in claim 68, further comprising the step of
comparing the calculated average heart rate against a predetermined
range to ensure that the calculated average heart rate lies within
the range to inhibit the effect of random noise.
70. A method as claimed in claim 62, wherein step (2) is carried
out by emitting infra-red over a limited angle.
71. A method as claimed in claim 70, wherein the limited angle is
adjustable.
72. A method as claimed in claim 62, wherein step (2) is carried
out by emitting electromagnetic radiation in the wavelength range
720 nm to 940 nm.
73. A method as claimed in claim 72, wherein the emitting means
emit electromagnetic radiation predominantly at a wavelength of 875
nm.
Description
FIELD OF INVENTION
[0001] The present invention relates to an apparatus and method for
determining the viability of eggs laid by egg-laying animals, and
in particular but not exclusively, to eggs laid by reptiles and
birds, for example parrots.
BACKGROUND
[0002] Once an egg has been laid by an animal, it must undergo a
period of incubation, either naturally or artificially, during
which time development of the young animal takes place. Many birds
for example, sit on an egg or clutch of eggs in order to regulate
temperature and humidity around the egg(s), such regulation being
crucial for the survival and proper development of the embryo
inside each egg. Other animals utilise different sources, for
example solar or geothermal energy, for this purpose.
Alternatively, incubation may be carried out and/or assisted by
man. Man-made incubators are well known that can hold a number of
eggs and which provide artificial temperature and humidity
regulation of the air around the eggs.
[0003] Many breeders and conservationists of egg-laying animals
need to know whether or not the embryo is alive and developing at
the proper rate inside the egg. Such knowledge is required
throughout the incubation period, and is important both in natural
and artificial incubation scenarios in order to maximise the
chances of survival of the young. In natural incubation, for
example a clutch of eggs brooded by a bird, if one or more embryos
does not survive, those eggs can become infected by bacteria and
endanger the remaining eggs. Furthermore, some species of parrot
for example the Palm Cockatoo, Black Cockatoo and Hyacinthine
Macaw, can only lay fertile eggs during a short period of time each
year and even then only incubate one egg at a time. If that egg
does not survive, the opportunity for successful breeding has been
missed for that year. Such scenarios can have serious implications
for endangered species, and for breeders and keepers of such birds
who exchange them for considerable sums of money. The situation is
analogous for many species of egg-laying animal.
[0004] At present there are two well known methods for checking the
fertility and development of eggs. The first method, known as
"candling", involves placing an egg in front of an intense light
source, for example tungsten halogen, so that the inside of the egg
is visible to the naked eye, and looking for signs of growth e.g.
vein development that is first visible after approximately four
days in parrot eggs. Over the next few days it is possible to check
for further growth by looking for increasing numbers and density of
veins and a growing "dark spot" in the centre of the egg. However,
there are three disadvantages with "candling", the first being that
a high intensity of light is required to see into the egg meaning
that it is exposed to high temperature levels that can damage or
kill the embryo in the egg if held over the light for too long.
Secondly, the "dark spot" grows at such a rate that after
approximately twelve days (in parrot eggs) it occupies so much of
the volume of the egg that the veins are no longer visible and it
is not possible to tell whether or not the young bird is alive.
Thirdly, some eggs are not suitable for "candling" such as raptors,
falcons, ducks and wild fowl, whose eggs range from dark green to
dark brown in colour, and other species whose shells are so dense
that the light from the lamp cannot pass through them. For such
eggs it is not possible to tell whether or not they are fertile and
alive in the first few days.
[0005] The second known method addresses the second and third
problems mentioned above. This method involves floating the egg in
still warm water and waiting for the egg to move as a result of
movement of the young animal inside. There are two disadvantages
associated with this method, the first being that the method is
unreliable and slow since it relies on a parameter that is
inherently random. Secondly, immersing the egg in water exposes it
to bacteria that can pass through the shell, particularly as the
egg is withdrawn from the water, when water on the surface of the
egg tends to be "sucked" in through the pores of the shell severely
reducing the egg's ability to self-regulate humidity. Once inside
the shell the bacteria and water are in an ideal environment at
37.degree. C. to multiply, potentially endangering the life of the
young animal.
[0006] U.S. Pat. No. 5,745,228 discloses an apparatus for
distinguishing live from infertile poultry eggs at high speed in
the presence of ambient (or background) light. The apparatus
comprises a photoemitter for emitting infra-red radiation located
directly opposite a photodetector. In use eggs pass at high speed
(10 inches per second is suggested) between the photoemitter and
photodetector on a conveyor. The photodetector is turned on and off
100 times per second in bursts of 250 .mu.s. The photodetector
takes readings when the photoemitter is actuated and when
deactivated; by subtracting these readings the effects of ambient
light on the signal are reduced. The apparatus only has sufficient
resolution to classify eggs into three groups namely, clear or
early dead, mid dead, and live. These results are not significantly
better than can be obtained by the aforementioned method of
candling.
[0007] FR 2 455 282 discloses an improved candling method in which
infra red light is passed through an egg in the presence of
background light. Light having passed through the detector is
detected and the output signal displayed on a visual display
screen. The viability of the egg is determined by comparison of the
relative intensity of the received signal either visually or
automatically.
[0008] However, the disadvantage with the aforementioned
publications is that only differences in the received intensity of
light from each egg can be compared in order to make an assessment
of the viability of an egg.
[0009] Thus, it is apparent that there is a need for an apparatus
and method of testing the viability of eggs that is more reliable,
that minimises the risks to which prior methods have exposed eggs,
and which facilitates maximisation of the chances of survival of
fertile eggs.
SUMMARY OF THE INVENTION
[0010] The present invention is based on an insight into the effect
that structures in viable eggs have on infra-red light passing
therethrough. This effect is present from approximately 5 to 12
days (depending on the species of animal) up until the animal
hatches from the egg.
[0011] According to one aspect of the present invention, there is
provided an apparatus for determining the viability of an egg,
which apparatus comprises shielding means, emitting means and
detecting means, the arrangement being such that, in use, the
shielding means inhibits exposure of an egg to background infra-red
radiation, said emitting means can emit electromagnetic radiation
at infra-red wavelength(s) that impinge on the egg, the apparatus
further comprising means for processing an output signal of the
detecting means to determine whether there is a cyclical variation
in the intensity of the infra-red radiation leaving the egg
corresponding to action of a heart, the existence of said cyclical
variation indicating that the egg is viable.
[0012] In one aspect the invention is particularly suitable for use
in determining the viability of rare and exotic eggs (e.g. parrots)
where speed of determination is less important than the accuracy of
the determination.
[0013] The use of infra-red light is preferred for two reasons, (1)
attenuation of infra-red light passing through eggs is much lower
than with light at optical wavelengths, and (2) infra-red light can
impinge on the egg for a much longer period without heating the
egg. The egg can be damaged by heat when candling with optical
light if the egg is left in front of the optical source for too
long.
[0014] Although the applicant believes that the periodic
attenuation of the received radiation will be superimposed on
optical light, it is too dangerous to place the egg in front of an
optical light source to enable the apparatus of the invention to
obtain the cyclical variation. This is because in order to
penetrate and pass right through the egg, particularly in dark
pigment eggs, light at optical wavelengths must be of such
intensity that the egg is in danger of becoming overheated if left
near the light source for any appreciable length of time (more than
3 or 4 seconds).
[0015] One advantage of at least preferred arrangements is that a
user can obtain a virtually instant indication of the viability of
the egg i.e. whether it is alive or not. Furthermore, such
arrangements mitigate the dangers to which the above mentioned
methods have exposed eggs. A further advantage is that much
"guesswork" is taken out of prior artificial incubation techniques
since the apparatus enables an accurate heart rate of the animal
inside the egg to be obtained which indicates whether incubating
conditions are optimised. A further advantage is that such
arrangements enable the viability of the egg to be determined
throughout the incubation period to hatching of the young animal.
"Background infra-red radiation" means radiation from unwanted
sources, for example artificial lighting and daylight. The
applicant has found that the presence of such radiation renders the
apparatus difficult to use and inhibits detection of the varying
intensity of the radiation that has passed through the egg. The
emitting means may emit infra-red at a single wavelength or over a
band of wavelengths simultaneously.
[0016] Further feature of the apparatus are set out in claims 2 to
11 to which attention is hereby directed.
[0017] Advantageously, the detecting means are shielded from
detecting electromagnetic radiation emitted directly from said
emitting means. This helps to ensure that the output from the
detecting means is meaningful. Since some radiation is reflected
off the shell of the egg, this shielding also inhibits radiation
that has not passed through the egg from reaching the detecting
means.
[0018] Preferably, the detecting means is positioned to inhibit
detection of electromagnetic radiation emitted directly from said
emitting means. In one embodiment, the detecting means is shielded
by positioning so that, in use, the egg lies between the emitting
means and detecting means. In another embodiment, the detecting
means is both positioned to inhibit detection of electromagnetic
radiation emitted directly from said emitting means and provided
with a physical shield.
[0019] Advantageously, said emitting means emit electromagnetic
radiation over a limited angle. This helps to ensure that the
detecting means only detects radiation that has passed through the
egg.
[0020] Preferably, the limited angle is adjustable. By making the
angle adjustable, and hence the amount of infra-red impinging on
the egg, a user is able to adjust the apparatus to achieve an
optimum output from the detecting means. In one embodiment the
apparatus is provided with a plurality of emitting means that each
have a different limited angle. In use, a user can switch between
each emitting means to obtain the best results.
[0021] Advantageously, the emitting means emit electromagnetic
radiation in the wavelength range 720 nm to 940 nm.
[0022] Preferably, the emitting means emit electromagnetic
radiation predominantly at a wavelength of 875 nm. The applicant
has found that this produces the strongest outputs from the
detecting means with chicken eggs.
[0023] Advantageously, the apparatus further comprises a support
means for supporting an egg in a position within the apparatus.
[0024] Preferably, the detecting means are located adjacent said
support means. In one embodiment the detecting means are located
within said support means, the arrangement being such that, in use,
electromagnetic radiation can reach the detecting means only by
passing through the egg. This is particularly advantageous because,
in use, the egg and support means enclose the detecting means so
that only radiation that has passed through the egg can be
detected.
[0025] Advantageously, the support means comprises a deformable
material that provides a point of contact with an egg, the material
deforming to part of the contours of the egg under the egg's
weight. This provides a "seal" inhibiting penetration of unwanted
infra-red radiation, that might be detected by the detecting
means.
[0026] Preferably, the deformable material comprises latex. In one
embodiment, the latex comprises a black dye. The applicant has
found this particularly effective since the combination inhibits
penetration of unwanted infra-red radiation and at the same time
provides a support that minimises potential for damage to the
egg.
[0027] Advantageously, the support means are mounted on a base.
[0028] Preferably, the base comprises an elastic material,
preferably foam rubber, to inhibit damage to an egg should it be
dropped onto the base.
[0029] Advantageously, the support means comprises a suction
cup.
[0030] Preferably, said shielding means comprises a housing having
a first member and a second member moveable with respect to the
first member from a position in which an egg can be inserted into
the apparatus to a position in which the egg is shielded from
background infra-red radiation. In one embodiment, the detecting
means and emitting means are mounted on the first member.
[0031] Preferably, the apparatus further comprises a power source.
One advantage of this is that the apparatus may be hand-held which
makes it easy to use in the field.
[0032] According to another aspect of the present invention there
is provided a method for determining the viability of an egg, which
method comprises the steps of: [0033] (1) placing an egg in an
environment that is shielded from background infra-red radiation;
[0034] (2) emitting electromagnetic radiation at infra-red
wavelength(s) from emitting means toward the egg; [0035] (3)
detecting at least a part of said electromagnetic radiation that
has passed through the egg with detecting means and generating an
output signal therefrom; and [0036] (4) processing said output
signal to determine whether there is a cyclical variation in the
intensity of the infra-red radiation leaving the egg corresponding
to action of a heart, the existence of said cyclical variation
indicating that the egg is viable.
[0037] Further steps of the method are set out in claims 31 to 49
to which attention is hereby directed.
BRIEF DESCRIPTION OF THE DRAWING
[0038] For a better understanding of the present invention,
reference will now be made by way of example to the accompanying
drawings in which:
[0039] FIG. 1 is a schematic cross section through a seven-day old
chicken embryo showing its embryonic membranes and embryonic blood
vessels;
[0040] FIG. 2 is a schematic cross section through an egg
containing the embryo of FIG. 1 shown at four points during its
development;
[0041] FIG. 3 is a schematic perspective view of part of an
apparatus in accordance with the present invention, the lid being
removed for clarity;
[0042] FIG. 4 is a schematic perspective view of a lid suitable for
use with the apparatus of FIG. 3;
[0043] FIG. 5 is a schematic view of the apparatus of FIG. 1 fitted
with the lid of FIG. 4;
[0044] FIG. 6 is a schematic cross section through an apparatus in
accordance with the present invention, part of the apparatus
omitted for clarity, in use determining the viability of an
egg;
[0045] FIG. 7 is a flow diagram showing the steps of a method in
accordance with the present invention;
[0046] FIG. 8 is a circuit diagram of the amplification and
filtering stages an apparatus in accordance with the present
invention;
[0047] FIG. 9 is a block diagram of the algorithm used to
manipulate the amplified output signal of the detector used in the
apparatus of the invention;
[0048] FIG. 10 is a schematic graph showing the method of detecting
the cyclical variation in intensity of light received by the
detector; and
[0049] FIGS. 11, 12 and 13 show various examples of traces of
voltage (Y-axis) against time (X-axis) that can been seen on a
screen of an apparatus in accordance with the present
invention.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0050] Referring to FIGS. 1 and 2, for an understanding of the
background to the present invention some details of a chicken
embryo 1 developing within a shell 2 are shown. It is to be noted
that the structure of the chicken egg is very similar to that of a
wide variety of egg-laying animals. The embryo 1 comprises a yolk
sac 3 within which blood vessels 5, known as the vitelline vessels,
extract nutrients and convey them to the embryo. Another structure
4 known as the allantois assists the respiratory cycle of the
embryo. As the embryo 1 grows the allantois 4 is pressed against
the inner surface of the shell 2 where the capillaries in the
allantois can readily exchange carbon dioxide for oxygen that has
passed through the pores of the shell. Under action of the animal's
heart the blood vessels 6 in the allantois 4 swell and contract in
a cyclical fashion. Furthermore, as is apparent from FIG. 2, the
allantois 4 grows as the embryo 1 develops so that it covers an
increasing surface area adjacent the inner side of the shell 2. The
respiratory function of the allantois 4 begins approximately at
three to four days from the beginning of the incubation period and
ceases when the chick breaks out of the egg and breathes of its own
accord. To the best of the applicant's knowledge and belief no
apparatus and method has been proposed up to now that takes
advantage of the cyclically variable blood flow through the vessels
of the allantois and/or the vitelline vessels, caused by the
animal's heart, to monitor the viability of the growing embryo
within the egg.
[0051] Referring to FIGS. 3 to 6, an apparatus generally identified
by reference numeral 10 comprises a housing 12 and a lid 14. As
shown in FIG. 3, the lid 14 can be mounted on the housing 12 via
inward projections 16 on the lid 14 that locate with recesses 18 on
the housing 12 and permit rotational movement of the lid 14 with
respect to the housing 12. The lid 14 is constructed from plastics
material that prevents the passage of infra-red radiation through
its walls.
[0052] The housing 12 comprises two sections, a first section 20
and a second section 22. The first section 20 comprises a liquid
crystal display 24, control buttons 26, a power source (not shown)
and various electronic processing equipment (not shown) that will
be described in greater detail below. The second section 22
comprises a box 28 open at its upper side and having five walls
constructed from plastics material that prevent passage of
infra-red radiation. Thus, when the lid 14 is in a closed position
on the box 28 the volume that is enclosed is shielded from
background infra-red radiation. A source 30 is mounted on the box
28 adjacent the second section 22 and is positioned so that it can
emit electromagnetic radiation into the box 28. The source 30 is an
infra-red (IR) emitter manufactured and sold by Hewlett Packard
(part number HSDL-4230) that can emit IR over a wavelength range of
720 940 nm, with peak intensity at approximately 875 nm. It has a
power rating of 75 mW/sr at 50 mA and a beam angle of 17.degree.,
the axis of the beam lying on a perpendicular to plane of the wall
on which it is mounted. The applicant has found that the power of
infra-red from the source 30 does not appear to cause any damage to
the egg under test. An infra-red detector 32 is mounted in the base
of box 28 and is designed and positioned to detect IR that has been
emitted by the source 30. The detector 32 is manufactured by Texas
Instruments as component TSL 250 and is available from Pacer
Components (Berkshire, England). It will be noted that the
radiation emitted from the source 30 does not directly intersect
with the detector 32.
[0053] Mounted on the bottom of the box 28 and around the detector
32 is a holder 34 which comprises an inverted suction cup
manufactured from latex so as to be deformable. The suction cup is
different to known suction cups in that a black dye has been added
during manufacture to inhibit passage of light at infra-red
wavelengths. In use, an egg can be placed on and supported by the
holder 34 and the latex deforms to the contours of that part of the
egg with which it is in contact. The egg can be supported in any
orientation by the holder 34. No suction is applied via the holder
34. The distance x as shown in FIG. 4 is 0.05 m, although this does
not appear critical and the source 30 may abut an egg or be further
away.
[0054] In use, the lid 14 of the apparatus 10 is opened and an egg
36 (see FIG. 6) who's viability is to be determined is placed on
the holder 34. The lid 14 is closed, placing the egg 34 in darkness
and shielding it from IR. One of the buttons 26 on the housing 12
is pressed and, under control of electronic circuitry (not shown)
in the second section 22, source 30 is activated and emits IR
radiation 38 toward the egg 34 continuously until the apparatus is
de-activated by the user. Upon reaching the egg 34 part of the
radiation 38 is reflected off the shell of the egg 34 and part
passes through the shell into the inside of the egg. It will be
noted that the holder 34 inhibits radiation that has been reflected
from the outside of the egg from being detected by the detector 32.
As shown in FIG. 5 some of radiation 38 is repeatedly reflected off
the inner side of the shell, some passes straight through and some
is ultimately reflected through 90.degree. i.e. in the direction of
detector 32. Upon leaving the egg 34 it is likely that some
radiation 38 passes across the allantois (not shown in FIG. 6)
inside the shell, and when in the early stages of incubation across
the yolk sac containing the vitelline vessels. As described above,
the allantois is responsible for intake of oxygen and expulsion of
CO.sub.2 from the egg as part of the respiratory cycle of the
developing animal. Blood vessels inside this membrane continually
swell and contract under the action of the animal's heart.
Accordingly, as IR radiation 38 passes across this structure, some
has to pass through more blood (when the blood vessels are swollen
or swelling) and some passes through less blood (when the blood
vessels are contracted or contracting). This results in a cyclical
variation in the intensity of the IR radiation leaving the egg 36
that is a direct function of the animal's heart rate. The
electrical output signal from the detector 32 also varies in the
same way, the variation being of the order of approximately 0.2 mV
to 1 mV. It is believed that is it is the blood vessels in the
allantois that are primarily responsible for causing the cyclical
variation in intensity of received infra-red. However, it might be
possible that other structures are responsible for the cyclical
variation, particularly the vitelline vessels when the egg is in
the early stages of incubation and the yolk sac is still large.
[0055] Referring to FIG. 7 the output signal from the detector 32
is processed by electronic processing equipment located in the
first section 20 of the housing 12. The signal is first amplified
and then filtered at stage 40.
[0056] Stage 40 is shown in greater detail in FIG. 8. The output
signal from the detector is of the order of approximately 200 mV
upon which the time varying voltage of the order of a few mV is
superimposed as described above. It is this time varying signal
that the circuitry is designed to extract and amplify. The output
signal first passes through a capacitor 48 to extract the time
varying part of the signal. This time varying signal passes to a
first gain stage 50 that applies a gain of 10 and also filters the
signal with the capacitor 52. The capacitor 52 acts as a low pass
filter with a filter corner frequency of 15 Hz i.e. the 15 Hz
component of the input signal is reduced by 3 dB at this stage. 15
Hz corresponds to a heart rate of approximately 900 beats per
minute, over which it is unlikely any animal's heart will beat, but
also well below the 50 Hz signal generated by mains electricity.
The signal then passes to a second gain stage 54 that applies a
gain of between 4.13 and 45.45, depending on the value of variable
resistor 56 (variable between 0 and 22 k.OMEGA.). The signal is
also filtered at stage 54, the capacitor 55 being a low pass filter
with a filter corner frequency of 33 Hz i.e. the 33 Hz component of
the input signal is reduced by 3 dB at this stage. Because of
electrical interference in the wires generated for example by
induction from mains power lines it is necessary to further filter
the signal; if the signal is not further filtered the time varying
signal corresponding to the variation in intensity of the received
IR would be totally drowned out by interference and noise.
Accordingly, the signal then passes through a first filter stage 58
that applies a gain of 1.068, onto a second filter stage 60 that
applies a gain of 1.58 and onto a third filter stage 62 that
applies a gain of 2.50. Each filter stage is a low pass filter
having a filter corner frequency set at 16 Hz i.e. the 16 Hz
component of the input signal is reduced by 3 dB at each stage.
Having been filtered, the signal passes through a final third gain
stage 64 that applies a gain of 10 and a final low pass filtering
of the signal with a corner frequency at 33 Hz. Accordingly the
overall gain on the time varying signal is between 1742 and 19180
remembering that this is because of the variable resistor 56, and
the signal has been filtered at 24 dB per octave (mainly due to the
effect of filtering at stages 50, 58, 60 and 62). In the actual
apparatus made by the applicant the variable resistor 56 can be
adjusted at the point of manufacture and is set to give the maximum
gain. However, it is not adjustable by the user. The signal then
leaves this section of the apparatus and moves onto the analogue to
digital converter.
[0057] Referring again to FIG. 7 at stage 42 the signal is
converted from analogue to digital and processed by a
microcontroller (not shown). The steps of the digital signal
processing are shown in greater detail in FIG. 9. The
microcontroller is programmed to set up a band stop filter 84, that
is it looks for that part of the signal having voltage amplitude
greater than a preset voltage and that part of the signal having
voltage amplitude lower than a preset voltage. The values of the
band stop filter are between 2.0V and 2.9V. The time varying signal
with which the apparatus is concerned is periodic by nature and
when an egg is appropriately positioned the peaks 86, 88 of this
signal will appear at either side of the band stop filter. Random
error noise 90 will also occasionally appear at either side of the
band stop filter; however, the algorithms programmed into the
microcontroller are designed to extract the periodic signal and
reject signals generated by random error noise that may not be
hidden by the band stop filter.
[0058] Referring to FIGS. 9 and 10 the first step 66 of the
algorithm involves monitoring the band stop filter 84 and waiting
for a signal to appear at either side. This monitoring is
continuous. Whilst the algorithm is waiting for its first pair of
signals 86, 88 the user sees a flat trace on the display and the
numerical value of beats per minute displayed to the user is zero.
When a first signal 86 does appear, the algorithm moves to step 68
in which it looks for a second signal 88; if it does not detect one
it simply continues to wait whilst still monitoring. If the
algorithm does detect a second signal 88 it moves to step 70 in
which the time interval in beats per minute (bpm) is calculated
between the detection of the first signal 86 and detection of the
second signal 88. In the same stage the algorithm checks whether
the calculated time interval falls within the range 30 to 600 bpm;
if it does not the signals are rejected, whereas if it does the
algorithm moves to step 72 in which the time interval is stored in
the microcontroller's memory. At step 74 the algorithm checks the
number of intervals that are stored in memory. If the number is
less than four, it waits for further time intervals to be received
at step 76. If the number is equal to four the algorithm calculates
the average bpm from the four intervals at step 78. Using four
intervals to calculate the average bpm is useful as this reduces
the chance of noise affecting the result. A further advantage is
that the average bpm will vary more gradually than a real time
display of the bpm that may fluctuate rapidly. Finally, the
algorithm checks that the calculated average bpm lies in the range
30 to 600 bpm at stage 80 (an animal's heart rate is unlikely to go
above 600 bpm; at present a high heart rate that the applicant has
measured was 250 bpm in a chicken egg (bantam)). If it is not, the
calculated average is discarded at stage 82. If it is in the range
the numerical value of bpm is displayed to the user on display 24
at stage 44 (see FIG. 7) together with a trace of voltage versus
time that represents the heart rate of the animal in the egg. The
trace is generated from the actual output signal, although it could
be generated from the calculated average bpm. However, using the
output signal enables the user to see if the apparatus has
generated a spurious result, for example if there is a lot of
repetitive noise in the signal. It should be noted that the
microcontroller only ever stores a maximum of four intervals. When
a new interval is received the oldest interval is removed to make
room for the new interval. In this manner the information displayed
to the user is always the latest and effectively provides a real
time display of the heart rate of the animal.
[0059] If no cyclical variation is obtained from the detector the
display 24 indicates that the egg is not viable and the trace shows
a flat line indicating IR being received by the detector 32 at a
constant rate (FIG. 11). If the egg is viable a trace similar to
that shown in FIG. 12 is seen.
[0060] The applicant has found that, even if the egg is viable, it
is not always possible to obtain a satisfactory output from the
detector 32. In particular, this occurs if the animal moves inside
the egg or if the infra-red does not pass through a sufficiently
big blood vessel as it exits the egg. If the animal is moving the
trace on display 24 is rapid, erratic and the pulse is exaggerated.
If the egg is in a bad position, the trace shows faint pulse line
i.e. greatly reduced in magnitude (FIG. 13), but not a flat line as
with a non-viable egg. In this situation, the algorithms at stage
42 cause the display to show a signal to the user either that
animal is moving or that the egg is badly positioned which prompts
the user to wait or re-position the egg. A user may need to
re-position the egg between 1 and 3 times to be sure that an egg is
not viable, and preferably repeat the process at several intervals
of 24 hours in order to be completely sure that the egg is not
viable. Although the apparatus indicates the viability almost
immediately, the eggs of some species are too valuable to discard
on the basis of one reading. The electronic processing equipment
continually monitors the received signal and as soon as a viable
signal is received the heart rate trace and beats per minute are
displayed.
[0061] The applicant has also found that the best signal is
obtained when the radiation impinges on an egg from its side i.e.
substantially perpendicular to its longitudinal axis, and the
detector 32 is located below the egg with its detection axis
substantially perpendicular to the axis of the source 30. However,
in the early stages of development of the egg, the detector 30 and
source 32 can be placed anywhere around the egg or the egg placed
at any orientation within the apparatus 10 to obtain a signal. When
the egg is more developed, the animal occupies so much of the
volume of the egg that only a narrow range of positions obtains a
satisfactory signal. One of these positions is shown in FIG. 4 and
is further advantageous because the egg can be readily supported in
this position. The applicant has also found that when nearly fully
developed, the best signals are obtained when the radiation
impinges on the rounded or "blunt" end of the egg and passes
through the air sack inside, thus still passing through the
structures mentioned above but not being obstructed by the
animal.
[0062] Important variations of the above embodiment are that the
electronic processing equipment may be separate from the box in
which the egg is placed i.e. the first section 20 may be separate
from the second section 22. If no signal is obtained from the
detecting means, the display 24 may prompt the user to move the egg
and/or re-activate the apparatus so that the viability is
determined over a number of interrogations, thus minimising the
chances of error.
[0063] The apparatus may be incorporated into known incubators to
provide an "all-in-one" arrangement for incubating eggs.
[0064] The apparatus described in the preferred embodiment is
designed to be hand-held and portable. However, this is not
essential.
* * * * *